“Wow, I’ve received a bunch of messages from people in Aus & NZ who are donating their ticket refunds to good causes: Parkinson’s research, animal rescue groups, fire victim funds, etc,” Katie, 46, tweeted on Tuesday.

“My heart is so full of joy to see this silver lining. Faith in humanity = restored. Thank you!” she added.

Neil Diamond and wife Katie in November 2016
Axelle/Bauer-Griffin/FilmMagic

Neil also shared his gratitude and appreciation to his fan base with a tweet of his own.

“This makes me smile. Thank you. Thank you to everyone for your outpouring of love and support. It makes a difference,” he tweeted, responding to his wife’s message.

Wow, I’ve received a bunch of messages from people in Aus & NZ who are donating their ticket refunds to good causes: Parkinson’s research, animal rescue groups, fire victim funds, etc. My heart is so full of joy to see this silver lining. Faith in humanity = restored. Thank you!

Due to the onset of the Parkinson’s disease, it has become “difficult to travel and perform on a large scale basis” but has yet to affect “his writing, recording and development of new projects,” according to the statement.

“I plan to remain active in writing, recording and other projects for a long time to come. My thanks goes out to my loyal and devoted audiences around the world,” Diamond said. “You will always have my appreciation for your support and encouragement. This ride has been ‘so good, so good, so good’ thanks to you.”

“Needless to say, I am dismayed at the news that one of the greatest songwriter/performers of my generation is having to curtail his activities due to illness,” Dolenz told PEOPLE in a statement. “Through his music, Neil brought untold joy to countless fans and to the world in general. I wish you all the best, Neil, and a remain a ‘Believer’ in everything you do.”

Meanwhile, Sedaka shared a memory from their childhood growing up together.

“Along with everyone else, I was shocked to hear this news,” he said to PEOPLE. “We lived across the street from each other in Brighton Beach, Brooklyn. He is the most talented of the singer/songwriters/performers that I watched hone their craft at the Brill Building. His recordings and his writings are just superb. He’s an all-around great guy. For all the joy he has brought to the world, I know it will come back to him tenfold. Sending all my love to him and his family.”